On 02-Apr-19 14:57, Jason Gunthorpe wrote:
> On Tue, Apr 02, 2019 at 10:05:00AM +0300, Gal Pressman wrote:
>>>>>> +#elif defined(DEBUG)
>>>>>> +#define ibdev_dbg(__dev, format, args...) \
>>>>>> + ibdev_printk(KERN_DEBUG, __dev, format, ##args)
>>>>>> +#else
>>>>>> +#define ibdev_dbg(__dev, format, args...) \
>>>>>> +({ \
>>>>>> + if (0) \
>>>>>
>>>>> Why isn't "empty macro" enough here and we need "if (0)"?
>>>>
>>>> I was wondering as well :).
>>>> This is copied from the netdev_dbg counterpart, my best guess is some kind of
>>>> compilation checks in case debug is disabled but I can't even convince myself..
>>>
>>> It is a trick to get the compiler to do a format & type check even
>>> when debug is disabled.
>>>
>>> Personally I prefer the much clearer non #define version
>>>
>>> __printf(2, 3)
>>> static inline void ibdev_dbg(const struct ib_device *dev, const char
>>> *format, ...) {}
>>>
>>> Instead of the macro tricks.
>>
>> Wouldn't that lose the format type checking? For example passing a pointer to %d?
>
> No, the static inline has the __printf attribute so the compiler checks it even
> though the inline is empty
Thanks, will change.
